1. Field of the Invention
The present invention relates generally to an open-end wrench, and more particularly to an open-end wrench, which is applicable to both an ordinary bolt and a worn bolt.
2. Description of the Related Art
A conventional open-end wrench has two jaws. The two jaws respectively have two holding plane faces in parallel to each other for holding and wrench an ordinary hexagonal bolt. The holding plane faces can be toothed to provide larger wrenching force. However, such wrench can hardly wrench a worn bolt. This is because the head section of the worn bolt is irregularly blunt. When making the holding plane faces of the jaws of the open-end wrench abut against the head section of the bolt to wrench the same, the holding plane faces are likely to slip over the corners of the head section of the bolt. Therefore, it is inconvenient to use such open-end wrench.
Taiwanese Patent Publication No. 319139 discloses an antislip open-end wrench as shown in FIG. 1. The head section of the open-end wrench 1 has a first jaw 11, a second jaw 12 and a bottom 13. Two recesses are formed on an inner face of the first jaw 11 in a position spaced from a free end of the first jaw 11 by a certain length and in a position close to the bottom 13 respectively. A boss section 111 is defined between the two recesses. Two arcuate protuberance sections 121 are formed on an inner face of the second jaw 12. A worn bolt head 3 can be held between the first and second jaws 11, 12 of the open-end wrench 1. The bolt head 3 has a width L. The inscribed circle of the bolt head 3 has a radius R. When making the inner faces of the jaws of the open-end wrench abut against the bolt head 3 to wrench the same, the effort point of the boss section 111 to the bolt head 3 will move so that the boss section 111 will still slip over the corners of the bolt head 3. Moreover, with respect to different bolts worn to different extents, the effort point of the boss section 111 can be hardly fixed. As a result, the boss section 111 is very likely to slip over the corners of the bolt head.
Therefore, it is inconvenient to use such open-end wrench. It is therefore tried by the applicant to provide a wrench, which is applicable to both an ordinary bolt and a worn bolt to easily wrench the same.